If you are going to raise the cap on contributions, then you'll have to raise the cap on benefits. If not, then its not an insurance system paid for by contributions but an entitlement as you denied earlier.
And you are incoherent again, you don't "stop paying" into social security at the cap. You just don't pay more social security taxes above the cap, you still pay the social security taxes for the base amount. Your benefits are also capped.